At more than 200 years, the maximum lifespan of the bowhead whale exceeds that of all other mammals. The bowhead is also the second-largest animal on Earth¹, reaching over 80,000 kg. Despite its very large number of cells and long lifespan, the bowhead is not highly cancer-prone, an incongruity termed Peto’s paradox². Here, to understand the mechanisms that underlie the cancer resistance of the bowhead whale, we examined the number of oncogenic hits required for malignant transformation of whale primary fibroblasts. Unexpectedly, bowhead whale fibroblasts required fewer oncogenic hits to undergo malignant transformation than human fibroblasts. However, bowhead whale cells exhibited enhanced DNA double-strand break repair capacity and fidelity, and lower mutation rates than cells of other mammals. We found the cold-inducible RNA-binding protein CIRBP to be highly expressed in bowhead fibroblasts and tissues. Bowhead whale CIRBP enhanced both non-homologous end joining and homologous recombination repair in human cells, reduced micronuclei formation, promoted DNA end protection, and stimulated end joining in vitro. CIRBP overexpression in Drosophila extended lifespan and improved resistance to irradiation. These findings provide evidence supporting the hypothesis that, rather than relying on additional tumour suppressor genes to prevent oncogenesis^3,4,5, the bowhead whale maintains genome integrity through enhanced DNA repair. This strategy, which does not eliminate damaged cells but faithfully repairs them, may be contributing to the exceptional longevity and low cancer incidence in the bowhead whale.

Postzygotic somatic mutations have been found associated with human disease, including diseases other than cancer. Most information on somatic mutations has come from studying clonally amplified mutant cells, based on a growth advantage or genetic drift. However, almost all somatic mutations are unique for each cell, and the quantitative analysis of these low-abundance mutations in normal tissues remains a major challenge in biology. Here, we introduce single-molecule mutation sequencing (SMM-seq), a novel approach for quantitative identification of point mutations in normal cells and tissues.

Aging associates with progressive loss of skeletal muscle function, sometimes leading to sarcopenia, a process characterized by impaired mobility and weakening of muscle strength. Since aging associates with profound epigenetic changes, epigenetic landscape alteration analysis in the skeletal muscle promises to highlight molecular mechanisms of age-associated alteration in skeletal muscle. This study was conducted exploiting the short-lived turquoise killifish Nothobranchius furzeri (Nfu), a relatively new model for aging studies. The epigenetic analysis suggested a less accessible and more condensed chromatin in old Nfu skeletal muscle. Specifically, an accumulation of heterochromatin regions was observed as a consequence of increased levels of H3K27me3, HP1α, polycomb complex subunits, and senescence-associated heterochromatic foci (SAHFs). Consistently, euchromatin histone marks, including H3K9ac, were significantly reduced. In this context, integrated bioinformatics analysis of RNASeq and ChIPSeq, related to skeletal muscle of Nfu at different ages, revealed a down-modulation of genes involved in cell cycle, differentiation, and DNA repair and an up-regulation of inflammation and senescence genes. Undoubtedly, more studies are needed to disclose the detailed mechanisms; however, our approach enlightened unprecedented features of Nfu skeletal muscle aging, potentially associated with swimming impairment and reduced mobility typical of old Nfu.

Background: The purpose of this study was to (1) perform the first analysis of bone-derived DNA methylation, (2) compare DNA methylation clocks derived from bone with those derived from whole blood, and (3) establish a relationship between DNA methylation age and 1-year mortality within the geriatric hip fracture population. Methods: Patients ≥65 years old who presented to a Level-I trauma center with a hip fracture were prospectively enrolled from 2020 to 2021. Preoperative whole blood and intraoperative bone samples were collected. Following DNA extraction, RRBS (reduced representation bisulfite sequencing) libraries for methylation clock analysis were prepared. Sequencing data were analyzed using computational algorithms previously described by Horvath et al. to build a regression model of methylation (biological) age for each tissue type. Student t tests were used to analyze differences (Δ) in methylation age versus chronological age. Correlation between blood and bone methylation ages was expressed using the Pearson R coefficient. Results: Blood and bone samples were collected from 47 patients. DNA extraction, sequencing, and methylation analysis were performed on 24 specimens from 12 subjects. Mean age at presentation was 85.4 ± 8.65 years. There was no difference in DNA extraction yield between the blood and bone samples (p = 0.935). The mean follow-up duration was 12.4 ± 4.3 months. The mortality cohort (4 patients, 33%) showed a mean ΔAgeBone of 18.33 ± 6.47 years and mean ΔAgeBlood of 16.93 ± 4.02 years. In comparison, the survival cohort showed a significantly lower mean ΔAgeBone and ΔAgeBlood (7.86 ± 6.7 and 7.31 ± 7.71 years; p = 0.026 and 0.039, respectively). Bone-derived methylation age was strongly correlated with blood-derived methylation age (R = 0.81; p = 0.0016). Conclusions: Bone-derived DNA methylation clocks were found to be both feasible and strongly correlated with those derived from whole blood within a geriatric hip fracture population. Mortality was independently associated with the DNA methylation age, and that age was approximately 17 years greater than chronological age in the mortality cohort. The results of the present study suggest that prevention of advanced DNA methylation may play a key role in decreasing mortality following hip fracture. Level of Evidence: Prognostic Level I. See Instructions for Authors for a complete description of levels of evidence.

Uveal melanoma is a melanocyte-derived malignancy of the eye with a high propensity for liver metastasis. Metastatic uveal melanoma is associated with high mortality and is poorly responsive to currently available therapies. Most uveal melanoma cases are driven by activating mutations in GNAQ and GNA11 genes, which convey oncogenic signaling through the mitogen-activated protein kinase (MAPK) pathway. Despite promising early results, safe doses of pharmacological inhibitors of the MAPK cascade failed to effectively control uveal melanoma in human trials. Considering the role of the RAC/PAK signaling axis as a co-regulator of the MAPK cascade, we set forth to investigate whether the efficacy of MAPK cascade inhibitors in pre-clinical models may be enhanced by direct inhibition of RAC and PAK proteins, or by indirect control of RAC via inhibition of guanylate biosynthesis. We observed that pharmacological inhibition of RAC, PAK and the key guanylate biosynthesis enzyme IMPDH significantly synergized with various inhibitors of the MAPK cascade in suppressing oncogenic signaling and the growth of uveal melanoma cells. In a mouse model, the addition of an IMPDH inhibitor to the treatment regimen significantly enhanced the ability of a MAPK cascade inhibitor to improve the survival of tumor-bearing animals. Targeting of the RAC/PAK axis provides a new strategy to increase the efficacy of targeted therapies in uveal melanoma. While RAC and PAK inhibitors are still undergoing pre-clinical development, clinically available inhibitors of IMPDH offer an opportunity to test the efficacy of this novel synergistic combination in the context of human disease.